Safety alert device

ABSTRACT

A danger warning system is proposed which is distinguished by the fact that the installation site of the modules connected to a central station of the danger warning system is determinable by the charging time of an energy store in the central station.

BACKGROUND INFORMATION

The present invention is directed to a danger warning system withmodules connected via at least one series connection, according to thegeneral class of the independent claim.

A danger warning system is known from DE 100 51 329 A1, according towhich various detectors and, possibly, other line elements are connectedwith a central station via a double-wire line. If a short circuitoccurs, the location where it occurs is determined by calculating thevoltage drop over the line sections leading up to this short circuit viathe current that flows through a measuring resistor. This makes itpossible to determine the length to the short circuit.

ADVANTAGES OF THE INVENTION

In contrast, the danger warning system according to the invention withmodules connected via at least one series connection having the featuresof the independent claim has the advantage that the installation site ofeach individual module is now possible via the charging time of anenergy store in the central station. As a result, it is possible thatthe installation site of the particular module can be determinedindependently of its logical address and without a manual adjustment,and it can be digitally processed further. This is necessary with alarger number of modules in particular.

Advantageous improvements of the danger warning system indicated in theindependent claim are possible due to the measures and furtherdevelopments listed in the dependent claims.

It is particularly advantageous that the energy store is configured as acapacitor, whereby the voltage is capable of being monitored via thecapacitor using a comparator circuit, and a counter for measuring thecharging time is provided. The configuration of a chain of resistors towhich the individual modules are connected further permits theinstallation site of the particular module to be counted off.

Means for reference measurement which check the capacitor at certainpoints in time are advantageously provided; this allows theoperatability of the capacitor to be detected. It is furthermoreadvantageous that switches are provided for discharging and forcharging. This makes it possible for the capacitor to be switched backand forth between these two modes.

DRAWING

An examplary embodiment of the invention is shown in the drawing andexplained in greater detail in the description below.

FIG. 1 shows a block diagram of a danger warning system, and

FIG. 2 shows a detailed illustration of the danger warning systemaccording to the invention.

DESCRIPTION

Danger warning systems are typically composed of a central processingunit, i.e., a central station, and a number of peripheral elements,i.e., modules, such as sensors for fire detection and for detectingentry into protected areas. These peripheral elements are combined intogroups and connected with the central processing device via interfacedevices.

In the present case, this interface device is referred to as a module.If a number of modules is now operated in a system, it is necessary todetermine the installation site of the individual module in the overallsystem.

This is achieved according to the invention by the fact that the modulesare triggered, via a control command, to close switches, in order toapply a specified voltage to a chain of resistors—which is how theseries connection between the central station and the modules isconfigured—and therefore to apply the specified voltage to this seriesconnection. An energy store in the central station can therefore becharged. The time required until the voltage value has reached the valueset at a comparator circuit is an indication of the installation site ofthe module. A further control command re-opens the switch on the module.To eliminate tolerances in the energy store, in particular in thecapacitor, a reference measurement is carried out with a switch beforeeach measurement series.

FIG. 1 is a schematic depiction of the principle design of a dangerwarning system. A central station 1 is connected with modules 2, 4 and 5via a serial line 3. Central station 1 processes data that come fromindividual modules 2, 4 and 5, which are alarms and other signalingdevices or actuators. When they are actuators, in particular, centralstation 1 performs control functions of the individual modules byforwarding control commands to the individual modules via line 3. Serialline 3 can be configured as a double-wire line; it is a bus in thiscase, in particular. Suitable methods are provided that allow the bustraffic to take place in orderly fashion. A further serial line 9 can beconnected to central station 1, with which said line further modules 6,7 and 8 are connected. It is possible that more than these two seriallines are connected to central station 1, in particular when loops areconnected that begin and end in central station 1.

FIG. 2 shows in detail how central station 1 detects the installationsite of the individual modules. One part of central station 1 is shownin the lower part of FIG. 2. A resistor 50 is connected to line 3, whichis connected at its other side with a switch SB, a capacitor C, and acomparator 80. On the first side, the resistor 50 is also connected vialine 3 with a switch SA and a first resistor in a chain of resistors.Capacitor C is connected on its other side with a switch SC which, inturn, is connected to ground. Switch SB is also connected to ground, onits other side. Switch SA is connected with operating voltage V on itsother side. On its other side, the first resistor in the chain ofresistors is connected with a switch S and the second resistor in thechain of resistors. This point is the slot for module 2, for example. Onits other side, the second resistor in the chain of resistors is alsoconnected with a switch S and the third resistor in the chain ofresistors. Slot 20 is provided here for a further module. On its otherside, the third resistor in the chain of resistors is also connectedwith a switch S and the fourth resistor in the chain of resistors. Slot30 is provided here for a further module. On its other side, the fourthresistor in the chain of resistors is connected with a switch S and afourth resistor in the chain of resistors. Slot 40 is provided here fora further module. The chain of resistors also terminates with aresistor, which is connected with a switch S. The last slot is labeledhere with the numeral 48. Switches S are connected on their other sideswith operating voltage V. Comparator 80 is connected via its other inputwith a resistor 60 and a resistor 70. Resistor 70 is connected on itsother side to ground, while resistor 60 is connected on its other sidewith operating voltage V. A signal is output at the outlet of comparator80 when capacitor C has reached a specified charging voltage as a resultof the charging. This time is counted by a counter in a part (not shown)of central station 1.

One of the modules is triggered first of all via a control command ofcentral station 1 to close one of the electronic switches S andtherefore apply voltage V to the chain of resistors. Switch SC is thenclosed. As a result, capacitor C can now charge. The time required untilthe voltage value has reached the value that is set at comparator 80 isan indicator of the installation site of the particular module. With afurther control command, switch S on the module is re-opened. Switch SBis then closed, in order to discharge capacitor C. Switches SB and SCare then re-opened, to be ready for a further measurement. To eliminatetolerances at capacitor C, a reference measurement is carried out beforeeach measurement series with switch SA. The control is carried out by aprocessor (not shown), which is connected via lines with switches SA, SBand SC in central station 1. As an alternative, a switching mechanismcan be used to activate the switches.

1. A danger warning system with modules (2, 4, 5, 6, 7, 8) connected via at least one series connection (3, 9), whereby means are provided in the danger warning system for determining the particular distance between the danger warning system and the particular module, wherein the modules (2, 4 through 8) are capable of being triggered by the danger warning system such that an energy store (C) is charged in the danger warning system, whereby the means for determining the particular distance evaluate the charging time of the energy store (C).
 2. The danger warning system as recited in claim 1, whereby the energy store is a capacitor (C), whereby the voltage is capable of being monitored via the capacitor using a comparator circuit (80), and a counter for measuring the charging time is provided, whereby the series connection (3) is configured as a chain of resistors.
 3. The danger warning system as recited in claim 1 wherein switches (SB, SC) are provided that can switch the energy store between an operating phase and a discharge phase.
 4. The danger warning system as recited in claim 1, whereby means (SA) are provided for performing a reference measurement of the energy store. 